1. Field of the Invention
The present invention relates to a film forming apparatus which forms a film of a ceramics material and a metallic material by using an AD (aerosol deposition) method, and a jetting nozzle used in the film forming apparatus.
2. Description of the Related Art
As a producing method of a piezoelectric film of a piezoelectric actuator used, for example, in an ink-jet head for an ink-jet printer or the like, a method called as an aerosol deposition method (AD method) is available. The AD method is a method of forming a piezoelectric film by jetting a substance (aerosol), in which fine particles of a piezoelectric material such as lead zirconate titanate (PZT) or the like is dispersed in a gas, toward a surface of a substrate such that the fine particles are collided and deposited onto the substrate. This producing method has been used not only for forming the film of a piezoelectric material, but also for forming a film of a ceramics material and a metallic material.
For example, in Japanese Patent Application Laid-open No. 2003-293159, an apparatus which performs a film formation by using such AD method is disclosed. This apparatus includes an aerosol forming chamber which generates an aerosol, a film forming chamber in which the aerosol generated is blown or jetted onto a substrate, and a nozzle which is provided inside the film forming chamber. The aerosol generated in the aerosol forming chamber is guided to the nozzle through a transporting pipe, and is jetted from the nozzle toward the substrate.
FIG. 9 shows a side cross-sectional view of a general nozzle 70 conventionally used in a film forming apparatus. The nozzle 70 as a whole is cylindrical shaped which is penetrated in a vertical direction, and an internal passage 71 through which the aerosol flows is formed inside the nozzle 70. An opening on a side of a lower end of the internal passage 71 defines a supply port 72 which is connected to the transporting pipe for the aerosol, and through which aerosol is received, and an opening on a side of an upper end of the internal passage 71 defines a jetting port 73 through which the aerosol is jetted. The aerosol enters from the supply port 72 into the nozzle 70, and flows upwardly through the internal passage 71, and is jetted from the jetting port 73 toward the substrate.
In some case, before particles in the aerosol are guided to such a nozzle, the particles are not reduced to sufficiently fine particles at a stage of aerosol generation, or the particles reduced to the fine particles are again aggregated while passing from the aerosol forming chamber to the nozzle, and are blown or sprayed onto the substrate in the form of aggregated particles having a large size. Since these aggregated particles have a large mass, collision energy at the time of colliding on the substrate is substantial, which in turn causes damage to the film and the like, thereby serving as a cause to hinder the formation of a thin and uniform film.